1. Technical Field
The present invention relates to a package structure for integrated circuit chips in general and, in particular, to a heat-dissipating package structure for integrated circuit chips. Still more particularly, the present invention relates to a heat-dissipating package structure having an efficient heat spreader for integrated circuit chips.
2. Description of the Prior Art
In recent years, integrated circuit (IC) chips have had a remarkable increase in device density and power consumption, mainly attributed to the decrease in transistor geometry and the increase in clock speed. In order to meet the package requirements for these high-density IC chips without adding to delay times, a packaging method known as flip-chip connection is becoming a preferred choice for packaging high-density IC chips. With the flip-chip connection method, IC chips are connected to a wiring by utilizing a number of small Pb.sub.95 Sn.sub.5 solder bumps. These small solder bumps enable a higher-density package to be achieved because the package area is substantially the same as that of the chip size and, also, high-speed signal propagation can be maintained due to the relatively short connection distances. Furthermore, because the entire surface of the IC chip may be utilized as a connection area, the number of external terminal pins on the package can also be increased.
For conventional wire-bonded IC chips, the backside of the IC chips is contacted directly, or through a solid member, to a heat sink. The heat generated from the IC chip will be dissipated first through conduction and then through convection to the atmosphere. Under the flip-chip connection method, the solder bumps between the IC chip and the wiring substrate are only about 100 .mu.m to 200 .mu.m in diameter; thus the heat dissipation characteristics of this type of package structure is not very satisfactory for IC chips that generate a large amount of heat. As a result, flip-chip type package structures are not very suitable for packaging high-power IC chips. Consequently, it would be desirable to provide an improved method for manufacturing a heat-dissipating package structure having a heat spreader for packaging high-density, high-power IC chips.